1. Field of the Invention
The present invention relates to a pattern-forming method, and a radiation-sensitive resin composition.
2. Discussion of the Background
Miniaturization of structures in various types of electronic devices such as semiconductor devices and liquid crystal devices has been accompanied by demands for miniaturization of resist patterns in lithography processes. Although fine resist patterns having a line width of about 90 nm can be formed using, for example, an ArF excimer laser at present, finer pattern formation is required in the future.
Therefore, pattern-forming methods involving resist compositions, developer solutions, exposure methods and the like have been improved. For example, high resolving abilities can be reportedly attained according to liquid immersion lithography, even if a light source of the same exposure wavelength is employed, similarly to the case in which a light source of a shorter wavelength is employed. Such liquid immersion lithography has drawn attention as a technique that achieves high resolution in manufacturing semiconductor elements which require a large amount of investment in equipment while suppressing an increase in costs.
However, due to elution of substances included in a resist into a liquid immersion medium, and the like in liquid immersion lithography, disadvantages have been suggested that adversely affect lithography characteristics by way of: deterioration of the resist film to impair performances thereof; regional changes of a refractive index of the liquid immersion medium due to eluted substances; contamination of the surface of a lens from eluted substances; and the like (see pamphlet of PCT International Publication No. 04/068242).
In addition, as a technique for increasing resolving power utilizing characteristic features of chemically amplified type resist materials, a technique in which a developer solution is used which is an organic solvent having lower polarity than that of aqueous alkali solutions has been investigated (see Japanese Unexamined Patent Application, Publication No. 2000-199953).